fix(jsonschema): emit unicode-safe patterns from concerto regexes

lib/codegen/fromcto/jsonschema/jsonschemavisitor.js

@@ -19,6 +19,56 @@ const { ModelUtil } = require('@accordproject/concerto-core');
 const { throwUnrecognizedType } = require('../../../common/util');
 const RecursionDetectionVisitor = require('./recursionvisitor');
 
+// Characters that may be escaped with a backslash in a unicode-mode regex
+// (`-` may only be escaped inside a character class)
+const UNICODE_ESCAPABLE = '^$\\.*+?()[]{}|/';
+
+/**
+ * Returns a regex source that is also valid in unicode mode, which JSON Schema
+ * validators such as ajv use to compile `pattern`. Concerto regexes have no `u`
+ * flag, so they may contain identity escapes such as `\<` that are rejected in
+ * unicode mode. Those escapes match the literal character either way, so the
+ * backslash is dropped. Sources that are already valid are returned unchanged.
+ * @param {string} source - the regex source
+ * @return {string} the unicode-safe regex source
+ * @private
+ */
+function toUnicodeSafePattern(source) {
+    try {
+        new RegExp(source, 'u');
+        return source;
+    } catch (err) {
+        debug('Regex is not valid in unicode mode, removing identity escapes', source);
+    }
+    let result = '';
+    let inClass = false;
+    for (let i = 0; i < source.length; i++) {
+        const char = source[i];
+        const next = source[i + 1];
+        if (char === '\\' && next !== undefined) {
+            if (/[A-Za-z0-9]/.test(next) || UNICODE_ESCAPABLE.includes(next) || (inClass && next === '-')) {
+                result += char + next;
+            } else {
+                result += next;
+            }
+            i++;
+        } else {
+            if (char === '[') {
+                inClass = true;
+            } else if (char === ']') {
+                inClass = false;
+            }
+            result += char;
+        }
+    }
+    try {
+        new RegExp(result, 'u');
+        return result;
+    } catch (err) {
+        return source;
+    }
+}
+
 /**
  * Convert the contents of a {@link ModelManager} to a JSON Schema, returning
  * the schema for all types under the 'definitions' key. If the 'rootType'
@@ -89,7 +139,7 @@ class JSONSchemaVisitor {
             } else if(validator) { // validator for uuid is not required.
                 // Note that regex flags are lost in this transformation
                 if (validator.getRegex()) {
-                    jsonSchema.pattern = validator.getRegex().source;
+                    jsonSchema.pattern = toUnicodeSafePattern(validator.getRegex().source);
                 }
                 if(validator.getMinLength()) {
                     jsonSchema.minLength = validator.getMinLength();

test/codegen/fromcto/jsonschema/jsonschemavisitor.js

@@ -334,6 +334,24 @@ describe('JSONSchema (samples)', function () {
             expect(schema.properties.myString.pattern).equal('abc.*');
         });
 
+        it('should generate unicode-safe patterns from regexes with identity escapes', () => {
+            const modelManager = new ModelManager();
+            modelManager.addCTOModel(`namespace test@1.0.0
+            concept Test {
+                o String noAngleBrackets regex=/^[^\\<\\>]*$/
+                o String escapedDash regex=/^a\\-b$/
+                o String alreadySafe regex=/^[\\w\\-]+\\.\\d+$/
+            }`);
+            const visitor = new JSONSchemaVisitor();
+            const schema = modelManager.accept(visitor, { rootType: 'test@1.0.0.Test'});
+            expect(schema.properties.noAngleBrackets.pattern).equal('^[^<>]*$');
+            expect(schema.properties.escapedDash.pattern).equal('^a-b$');
+            expect(schema.properties.alreadySafe.pattern).equal('^[\\w\\-]+\\.\\d+$');
+            Object.values(schema.properties)
+                .filter(property => property.pattern)
+                .forEach(property => expect(() => new RegExp(property.pattern, 'u')).to.not.throw());
+        });
+
         it('should inline types for simple model', () => {
             const modelManager = new ModelManager();
             modelManager.addCTOModel( MODEL_SIMPLE );

test/verification/jsonschema.validate.test.js

@@ -49,6 +49,11 @@ async function verifyJsonSchemaCompiles(modelManager, visitorOptions = {}) {
         const ajv = new Ajv({ strict: false });
         try {
             ajv.compile(schema);
+            // ajv only compiles definitions that are referenced, so compile
+            // each definition through a $ref to check all of them
+            Object.keys(schema.definitions || {}).forEach(name => {
+                ajv.compile({ ...schema, $ref: `#/definitions/${name}` });
+            });
         } catch (err) {
             throw new Error(err.message);
         }